Poly(ADP-ribose)polymerase, hereinafter sometimes to be abbreviated as “PARP”, is an intranuclear enzyme that utilizes nicotinamide nucleotide (NAD) as a substrate, cleaves the bond between nicotinamide and ribose, transfers ADP-ribose residue into a protein, and causes addition polymerization of plural ADP-ribose residues. This enzyme is attractive as an apoptosis-related enzyme, which is considered to be activated by recognizing the nick of DNA damaged by a free radical, such as nitrogen monoxide, active oxygen and the like, which is produced in the lesion during ischemia, and have a primary role to aid DNA repair.
It is considered in recent years that the activation of PARP decreases intracellular NAD, a large amount of ATP is consumed to compensate for the decrease, as a result of which intracellular energy is depleted, and the cell is driven to death. In an experiment using a PARP knockout mouse, it has been clarified that a cultured nerve cells show resistance to disorders due to excitatory amino acids, such as nitrogen monoxide, NMDA (N-methyl-D-aspartate) and the like, and that it shows a tremendous protective effect by inhibiting cerebral infarction caused by cerebral ischemia by not less than 80% (Eliasson M J L. et al., Nature Med., 3, 1089–95 (1997)).
However, none of the reported PARP inhibitors to date has subjected to a clinical trial as a therapeutic agent for cerebral infarction. As the reported PARP inhibitors to date, for example, 5-substituted-3,4-dihydro-2H-isoquinoline derivatives (JP-A-H2-124874), 1,11b-dihydrobenzopyrano[4.3.2-de]isoquinolin-3-one derivatives (WO99/11645), 3,4-dihydro-5-[4-(1-piperidinyl)-butoxy]-1(2H)-isoquinoline (each of WO99/08680 and WO99/11649), pyrimidine derivatives (WO00/42025), benzimidazole derivatives (each of WO00/64878 and WO00/68206), phthalazine derivatives (each of WO00/67734 and WO00/44726), quinazolinone derivatives (each of WO02/48117 and WO02/44157) and the like are known, but the PARP inhibitory activity thereof is not very strong.
Moreover, JP-B-S46-12454 discloses isoquinoline derivatives having an analgesic action and a hypoglycemic action, U.S. Pat. Nos. 1,174,272 and 1,062,357 respectively disclose quinazoline derivatives having a hypotensive action, GB Patent Nos. 1174272 and 1062357 and DE Patent No. 2121031 respectively disclose quinazoline derivatives having a hypotensive action, U.S. Pat. No. 4,808,595 discloses furopyridine derivatives having an intraocular pressure lowering action, and JP-A-S64-42472 discloses quinazoline derivatives having a cerebral dysfunction improving action, but none of these takes note of the PARP inhibitory action.